1. Field of the Invention
The present invention relates generally to lubrication systems for use in air-cooled, overhead cam internal combustion engines. More particularly, it relates to an improved lubrication system for such an engine, wherein the presence of lubricating oil within the pump is assured at all times, and the returning lubricating oil is cooled by the flow of cooling air over the engine.
2. Description of the Prior Art
Air-cooled, internal combustion engines equipped with overhead cams are known. In the conventional engine of this type, a lubricant pump is located above the level of the lubricating oil stored in the engine crankcase. As a result, when the engine is initially operated after its manufacturing or its repairing, only air is pumped through the lubrication system. This occurs because time is required to draw lubricating oil from the reservoir into the pump. The result of this arrangement is that detrimental friction occurs between the components, which can cause premature excessive wear, or even seizures. In order to avoid this problem, a common practice is to previously apply lubricant to the pump by hand. However, this method involves considerable labor, and may not be totally effective. Further, the circulation of the lubricating oil may fall behind, resulting in damage to the engine.
The conventional engine of this type also requires special oil conduits leading to and from the cylinder head region, which add expense to the engine construction. Further, cooling of the lubricating oil is sometimes less than adequate, because of the location of return passages.
There is need for an improved lubrication system for air-cooled, overhead cam engines, designed to overcome these problems with conventional lubrication systems for such engines. The present invention is intended to satisfy that need.